Read More button... where does the code snippet go?

Hello.

I've just installed the theme, upgraded to the premium version and I'm very happy to support a Canadian based business (loved my time in BC and feel "stuck" in Ontario). I'm in the process of switching my site over to WordPress, copying content, playing with feature images (most of the old site was simply text based) and currently the WP version is a subdomain. I tried a couple of themes then found this one and I'll naturally have some questions as the days go on...

So, my first question is about the Read More button. I've read the documentation:

https://docs.generatepress.com/article/activating-read-custom-excerpt/

I'd like to continue using excerpts and have the button displayed as well. Where do I place the code? And I'm assuming I use the theme editor in the WP dashboard.

Oh, and unrelated but... how do I display a profile picture here. I didn't notice an option when editing my profile.

Thanks in advance,

Joseph